260 C. T. BRUES, 
others. It is furnished with rather long legs provided with the bul- 
bous feet which seem to be characteristic of all Xenos triungulins, 
has small but well developed eyes, and runs actively about after it 
has once left the body of the Polistes. From my own observations 
it would seem that more likely they take but very little food during 
this instar, which is probably of short duration. 
As has been suggested by SHARP (1899), there is undoubtedly a 
great change at the ecdysis between the triungulin and first legless 
larva, but the structure of the first larva is so simple and degenerate 
that the loss of mouth-parts, legs and caudal setae, coupled with an 
elongation of the blind alimentary tract would give rise to the con- 
dition seen in the first larva. 
The alimentary tract of the first larva extends throughout the 
entire length of the body, but I have been unable to detect any dis- 
tinct anal opening. The mouth opens anteriorly on the lower surface 
of the head, and is not provided with any chitinous structures which 
resemble mouth-parts in the least. The pharynx is very narrow, but 
immediately behind it the alimentary tract widens out rather suddenly 
until its diameter becomes equal to one-third that of the entire body. 
The cells composing the walls of the pharynx are arranged in the 
form of a regular epithelium of columnar cells. These cells cease at 
the point where the oesophageal commissures pass and give place to 
intestinal cells. No divisions of the alimentary tract posterior to the 
pharynx can be distinguished, either by form or cell structure; 
posteriorly it is rounded off and attached to the hypodermis by a 
small mass of cells, although no external opening could be observed. 
Worthy of notice here also are metameric constrictions of the wall of 
the intestine. These are very distinctly marked and seem to cor- 
respond to the segmentation of the larva, at least each portion which 
is constricted off corresponds to one of the leg-like protuberances 
upon the ventral surface of the body (see Fig. 22). This condition 
is quite peculiar and does not seem to occur in any other insect 
larvae, at least to such an extreme degree. As the gut occupies 
nearly all of the body cavity in the youngest larva, it is not hard to 
see how it might become constricted metamerically from mere physical 
causes. The cells lining the alimentary tract are extremely irregular 
and vary greatly in size, nowhere forming a regular epithelium. Many 
of the larger ones are continually becoming greatly swollen and are 
detached to float about in the lumen, where they gradually become 
disintegrated to form a substance that stains like yolk. In very young 
